6 * compressed data are seuences of byte codes.
7 * if the first byte b has the 0x80 bit set, the next (b^0x80)+1 bytes
8 * are data. otherwise, it's two bytes specifying a previous string to repeat.
11 _twiddlecompressed(uchar *buf, int n)
21 for(j=0; j<k; j++, buf++)
29 _compblocksize(Rectangle r, int depth)
33 bpl = bytesperline(r, depth);
34 bpl = 2*bpl; /* add plenty extra for blocking, etc. */